Life history variation along a salinity gradient in coastal marshes

Abstract

Coastal habitats are susceptible to changes in the environment associated with alterations in salinity. A field study was conducted on natural populations of the sailfin molly Poecilia latipinna, the western mosquitofish Gambusia affinis and the least killifish Heterandria formosa collected from coastal marsh sites along a salinity gradient, to investigate the influence of salinity on body condition and reproductive life history traits. In brackish marsh sites male P. latipinna had the best body conditions, while females had similar body conditions across all 3 marsh types. Female P. latipinna had greater reproductive allotment and fecundity in brackish marshes, where this fish was most abundant. Specimens of G. affinis collected from fresh marsh sites had less favorable body condition, and females had lower reproductive allotment and fecundity than those collected from higher salinities. While G. affinis was more abundant in freshwater marshes than in higher salinity marshes, this higher abundance did not correspond with a better body condition or higher reproductive effort, suggesting that G. affinis may be stressed in freshwater. There was no difference in the conditions between (both male and female) H. formosa from fresh and intermediate marshes. Female H. formosa from fresh marshes had a similar reproductive allotment and lower fecundity than those from intermediate marshes. The 3 species exhibited different life history patterns along the salinity gradient, and some of these patterns conflicted with expectations based on species abundances. When assessing habitat quality along an environmental gradient, measures of abundance should be accompanied by more sensitive indicators of environmental stress.

Influence of environmental stress on age- and size-at-maturity: genetic and plastic responses of coastal marsh fishes to changing salinities

“…They also reported that regardless of their population of origin, G. affinis raised in fresh water had lower survival and were smaller at maturity than fish raised in brackish water, demonstrating phenotypic plasticity for several life history traits in environments with different salinity levels (Stearns and Sage 1980). Similarly, G. affinis collected from intermediate and brackish marshes (where they were least abundant) exhibited higher body condition and reproductive effort than those mosquitofish from fresh marshes (Martin et al 2009). It has been demonstrated that G. affinis did not vary their marginal metabolic scope when exposed to salinities ranging from 0 to 20 ppt (Akin and Neill 2003).…”

“…This surrogate for environmental salinity was used successfully by Purcell et al (2008) to investigate local adaptation to salinity in G. affinis. In May-September 2004, G. affinis and H. formosa individuals were collected using a dip net along a salinity gradient from five populations (at least 2 km apart) within each of three marsh types: fresh (0-1 parts per thousand (ppt)), intermediate (1-8 ppt), and brackish (8-15 ppt) in the Terrebonne Basin of southeastern Louisiana (see Martin et al 2009). Because H. formosa rarely occurred in the brackish marsh sites, collections of this species were limited to fresh and intermediate marshes.…”

“…Although considered euryhaline (wide salinity tolerance), G. affinis and H. formosa are most abundant in freshwater habitats (Hitch et al 2011). However, in a study of natural populations, Martin et al (2009) found G. affinis collected from fresh marsh habitats exhibited indications of environmental stress in the form of lower body condition, reproductive allotment, and fecundity.…”

Monophyly of Heterandriini (Teleostei: Poeciliidae) revisited: a critical review of the data

“…Poeciliids are characterized by a suite of derived characters including the position of the pectoral fins high on side of the body, an anterior placement of the pelvic fins ventral to the pectoral fins, the presence of pleural ribs on the first several haemal arches, a bony cap on the ventral hypohyal lying over the anterior facet of the anterior ceratohyal, and supraorbital laterosensory pores with neuromasts embedded in fleshy grooves (Ghedotti, 2000). Despite the widespread use of poeciliid fishes in ecological and evolutionary studies (e.g., Rauchenberger, 1990;Meyer et al, 1994;Borrowsky et al, 1995;Marcus & McCune, 1999;Spencer et al, 1999;Spencer et al, 2000;Morris et al, 2001;Kallman et al, 2004;Gutierrez-Rodriguez et al, 2007a, 2007bReznick et al, 2007;Leberg & Firmin, 2008;Purcell et al, 2008;Martin et al, 2009;Pollux et al, 2009;Meredith et al, 2010;Pires et al, 2010;Albert & Johnson, 2011), the phylogenetic interrelationships among poeciliid species remain incompletely resolved.The family Poeciliidae comprises three subfamilies that are restricted to fresh and brackish continental waters: Poeciliinae, Procatopodinae, and Aplocheilichthyinae (Ghedotti, 2000;Lucinda, 2003;Hrbek et al, 2007). The Poeciliinae includes at least 228 species distributed across much of the tropical and subtropical portions of the Americas, from the La Plata estuary of northern Argentina to southeastern United States, with species richness reaching a zenith in Middle America and the West Indies (Rosen & Bailey, 1963;Lucinda, 2003;Hrbek et al, 2007;.…”

Reproductive strategies of the marine fishes from the southwest Atlantic Ocean: an application of histological and image processing techniques

“…Thus, fishing activities, climate changes and the environment are the main factors driving changes in fish reproductive life history, affecting oocyte maturation, size-age at the first maturity, spawning frequency, longevity, fecundity, egg size and offspring size (WAGGY et al, 2006;MARTIN et al, 2009;MUNDAY, 2011;WIEDMANN et al, 2014). However, the oocyte production in S. brasiliensis (N, RN, OPD i and OPD) was similar to the S. rastrifer, although they were sampled in different environments.…”